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1. A sandwich-type cluster containing Ge@Pd3 planar fragment flanked by aromatic nonagermanide caps

   https://doi.org/10.1038/s41467-020-19079-z  

   Xu, Hong-Lei; Tkachenko, Nikolay V.; Wang, Zi-Chuan; Chen, Wei-Xing; Qiao, Lei; Muñoz-Castro, Alvaro; Boldyrev, Alexander I.; Sun, Zhong-Ming (December 2020, Nature Communications)

   null (Ed.)

   Abstract Sandwich-type clusters with the planar fragment containing a heterometallic sheet have remained elusive. In this work, we introduce the [K(2,2,2-crypt)] 4 {(Ge 9 ) 2 [ η 6 -Ge(PdPPh 3 ) 3 ]} complex that contains a heterometallic sandwich fragment. The title compound is structurally characterized by means of single-crystal X-ray diffraction, which reveals the presence of an unusual heteroatomic metal planar fragment Ge@Pd 3 . The planar fragment contains a rare formal zerovalent germanium core and a peculiar bonding mode of sp 2 -Ge@(PdPPh 3 ) 3 trigonal planar structure, whereas the nonagermanide fragments act as capping ligands. The chemical bonding pattern of the planar fragment consists of three 2c-2e Pd-Ge σ-bonds attaching Pd atoms to the core Ge atom, while the binding between the planar fragment and the aromatic Ge 9 ligands is provided by six 2c-2e Pd-Ge σ-bonds and two delocalized 4c-2e σ-bonds. The synthesized cluster represents a rare example of a sandwich compound with the heteroatomic metal planar fragment and inorganic aromatic capping ligands. 

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2. Synthesis of Square Planar Cu ₄ Clusters

   https://doi.org/10.1002/anie.202209529  

   Osei, Manasseh Kusi; Mirzaei, Saber; Bogetti, Xiaowei; Castro, Edison; Rahman, Mohammad Azizur; Saxena, Sunil; Hernández Sánchez, Raúl (September 2022, Angewandte Chemie International Edition)

   Abstract Template‐assisted synthesis of well‐defined polynuclear clusters remains a challenge for [M₄] square planar topologies. Herein, we present a tetraamine scaffold^RL(NH₂)₄, where L is a rigidified resorcin[4]arene, to direct the formation ofC₄‐symmetric^RL(NH)₄Cu₄clusters with Cu−Cu distances around 2.7 Å, suggesting metal‐metal direct interactions are operative since the sum of copper's van der Waals radii is 2.8 Å. DFT calculations display HOMO to HOMO‐3 residing all within a 0.1 eV gap. These four orbitals display significant electron density contribution from the Cu centers suggesting a delocalized electronic structure. The one‐electron oxidized [Cu₄]⁺species was probed by variable temperature X‐band continuous wave‐electron paramagnetic resonance (CW‐EPR), which displays a multiline spectrum at room temperature. This work presents a novel synthetic strategy for [M₄] clusters and a new platform to investigate activation of small molecules. 

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3. Group 14 Central Atoms and Halogen Bonding in Different Dielectric Environments: How Germanium Outperforms Silicon

   https://doi.org/10.1002/cplu.202100294  

   Donald, Kelling_J; Prasad, Supreeth; Wilson, Kaitlin (August 2021, ChemPlusChem)

   Abstract The nature of halogen bonding under different dielectric conditions remains underexplored, especially for inorganic systems. The structural and energetic properties of model halogen bonded complexes (R₃M−I—NH₃for R=H and F, and M=C, Si, and Ge) are examined computationally for relative permittivities between 1 and 109 using an implicit solvent model. We confirm and assess the exceptionally high maximum potentials at the sigma hole on I (V_s,max) in F₃Ge−I relative to cases where M=C or Si. In particular, Ge far outperforms Si in mediating inductive effects. Linear relationships, typically with R²>0.97, are identified betweenV_s,max, the full point charge on I in R₃M−I, and the interaction energy, and optimized I—N distance in the complexes. An anomalous trend is identified in which, for each M, F₃M−I—NH₃becomeslessstable as the optimized I—N distance getsshorterin different dielectric environments; it is explained using the F−I—NH₃complex as a reference. 

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4. Low concentrations of Cu ²⁺ in synthetic nutrient containing wastewater inhibit MgCO ₃ -to-struvite transformation

   https://doi.org/10.1039/D0EW01035A  

   Barčauskaitė, Karolina; Drapanauskaitė, Donata; Silva, Manoj; Murzin, Vadim; Doyeni, Modupe; Urbonavicius, Marius; Williams, Clinton F.; Supronienė, Skaidrė; Baltrusaitis, Jonas (March 2021, Environmental Science: Water Research & Technology)

   null (Ed.)

   Simultaneous major nutrient nitrogen (N) and phosphorus (P) recovery from wastewater is key to achieving food–energy–water sustainable development. In this work, we elucidate the reaction kinetics, crystalline structure and chemical composition of the resulting solid precipitate obtained from simulated N and P containing wastewater solution using widely abundant low solubility magnesite (MgCO 3 ) particles in the presence of common transition metal ions, such as zinc (Zn 2+ ) or copper (Cu 2+ ). We show that up to 100 ppm Zn 2+ from the simulated wastewater can be incorporated into the struvite lattice as isolated distorted Zn 2+ while even at very low concentrations of ∼5 ppm Cu 2+ ions almost completely inhibit struvite crystal formation. The resulting solid precipitate distinctly affects soil microbial biomass carbon and soil dehydrogenase enzyme activity. These results show a cautionary case where abundant natural mineral MgCO 3 exhibits very different chemistry in Cu 2+ containing simulated wastewater and does not readily adsorb or retain NH 4 + and PO 4 3− ions, unlike less sustainable but more water-soluble magnesium sources, such as MgCl 2 , at the equivalent [Mg 2+ ] : [NH 4 + ] : [PO 4 3− ] molar ratio of 1.4 : 1 : 1. 

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5. Ca ₂ Ga ₄ Ge ₆ and Ca ₃ Ga ₄ Ge ₆ : Synthesis, Structure, and Electronic Properties

   https://doi.org/10.1002/zaac.202100342  

   Hodge, Kelsey L; Davis, H Olivia; Koster, Karl G; Windl, Wolfgang; Moore, Curtis E; Goldberger, Joshua E (August 2022, Zeitschrift für anorganische und allgemeine Chemie)

   Abstract During the search for transition metal‐free alkyne hydrogenation catalysts, two new ternary Ca−Ga−Ge phases, Ca₂Ga₄Ge₆(Cmc2₁, a=4.1600(10) Å, b=23.283(5) Å, c=10.789(3) Å) and Ca₃Ga₄Ge₆(C2/m, a=24.063(2) Å, b=4.1987(4) Å, c=10.9794(9) Å, β=91.409(4)°), were discovered. These compounds are isostructural to the previously established Yb₂Ga₄Ge₆and Yb₃Ga₄Ge₆analogues, and according to Zintl‐Klemm counting rules, consist of anionic [Ga₄Ge₆]⁴⁻and [Ga₄Ge₆]⁶⁻frameworks in which every Ga and Ge atom would have a formal octet with no Ga−Ga or Ga−Ge π‐bonding. These compounds are metallic, based on temperature dependent electrical resistivity and thermopower measurements for Ca₃Ga₄Ge₆, along with density functional theory calculations for both phases. Unlike the highly active 13‐layer trigonal CaGaGe phase, these new compounds exhibit minimal activity in the semi/full alkyne hydrogenation of phenylacetylene, which is consistent with previous observations that the lack of a formal octet for framework atoms is essential for catalysis in these Zintl‐Klemm compounds. 

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